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Craftsman Air Compressor 3 gallon 1 HP oil lubricated model number 921.153101

I purchased the Craftsman Air Compressor 3 gallon 1 HP oil lubricated model number 921.153101, serial number 757588 in 2008. Until recently it has performed well with no problems. During operation recently, the sound of the unit noticeably changed and the compressor could not develop pressure enough to satisfy the pressure activated shutoff switch, it only managed 80+/- psi. I removed the cylinder head expecting to see broken or worn Reed Valves-they appeared to be ok, I then removed the piston cylinder expecting to see broken or damaged ring, they also seemed ok, the cylinder walls are smooth and unseared. I reassembled everything and although it runs the pressure developed progressively drops with subsequent startup. I would appreciate some accurate insight to the probable culprit of the problem before I merely buy parts and fix the problem by process of elimination.

Air Compressors , Craftsman , Tools
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2 Answers from these members:
Manage My Life
Hello There,
I see your having a little trouble with your Air Compressor. My best advise for you is to take your Air Compressor in to the nearest Sears Repair Center. I attached the link below that will take you to the store locator and then you can find the nearest store.I hope this helps!!
by Manage My Life
June 22nd, 2010
Answered in 30 minutes
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Manage My Life
If there are no air leaks such as at the pressure relief valve or the outlet tube and you torqued all of the head bolts to the proper specifications that would leave either a defective check valve or piston rings. The only accurate way to test the rings would be to run a compression test.

To do this you would have to be able to attach a standard automotive compression tester to the outlet port of the compressor where the outlet tube is attached to the compressor head. You may need to get some plumbing fittings from your local hardware store to adapt the tester

Operate the compressor for a few seconds and observe the gauge on the tester.

If the gauge drops the rings are bad.

If it does not drop then the rings are good and the problem should be the check valve.
by Manage My Life
June 24th, 2010
0 votes
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